A number of ruthenate compounds are known in the art to be useful as anti-tumor compounds. See e.g., U.S. Pat. No. 4,843,069: PCT Publication No. WO 9736595, and US Application Publication No. 2005032801. In particular, the ruthenium complex salts indazolium trans-[tetrachlorobis(1H-indazole)ruthenate (III)] and sodium trans -[tetrachlorobis(1H-indazole)ruthenate (III)] have been shown to be highly potent in inducing apoptosis in certain types of cancer. See U.S. Pat. No. 7,338,946.